Bovine mastitis is considered as the disease causing the largest economic loss to milk production, due to the reduction of quantity and compromise to the quality of the produced milk, or even for the full loss of secreting capacity of the mammary gland. Mastitis is a mammary gland inflammation, usually of infectious nature, which may be considered as clinical or subclinical. Clinical mastitis has clear signs, such as edema, increase in temperature, hardening, pain in the mammary gland, grains, pus or any change in milk characteristics. In the subclinical form of mastitis, no macroscopic changes are seen, but rather changes in milk composition, i.e., there are no visible signs of udder inflammation.
In Brazil, subclinical mastitis is highly incident, with indexes between about 45 and 97.00% of bovine stocks and the reduction in milk production is of about 25-43.0%. This is a considerable figure, and worrying for the national milk industry.
Ethyology of mastitis is complex and multiple, wherein the main ethyological agents are bacteriae from genus Staphylococcus and Streptococcus. Mastitis can be classified as contagious or environmental, wherein the first one is mainly caused by Staphylococcus aureus, S. epidermidis, Streptococcus agalactiae, S. dysgalactiae, Corynebacterium bovis and Actinomyces pyogenes, which are responsible for about 80% of mastitis cases. In environmental mastitis, the main agents include Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes, Streptococcus faecium, Nocardia spp and Pseudomonas aeruginosa. 
Besides being the most important sanitary problem as related to milk production, mastitis, as indicated above, is also responsible for large economical losses caused by the reduction in the quality and quantity of milk, costs with medicine, veterinary care and the substitution of breeding animals.
In the past few years, plants have been more and more highlighted as the main targets for scientific studies, with a large variety of structures, chemical properties and biologically active substances. Many vegetal species have given significant contributions to the development and synthesis of new pharmaceuticals. Brazil is considered so far as the country with the most varied genetic diversity in the world, with about 55,000 catalogued species from an estimated total between 350,000 and 550,000 species. For this reason, scientific research in the botanical, agronomical, phytochemical, genetic and pharmacological areas have increased in an attempt to search and validate bioactive compounds for therapeutic purposes.
Microorganism resistance and side effects caused by the continued use of synthetic medicines take the population to search for natural products. Also, phytotherapics have synergy between components as present in the plant with their action and, since they have a large number of substances, they work against different molecular targets, thus causing less side effects. Furthermore, since the costs for research and development for phytotherapic medicines are much lower than those related to synthetic medicines, they are more accessible and the number of phytotherapics is largely increasing in the market nowadays.
Another aspect to be considered is the increase in microorganism resistance to clinical antibiotics, which requires the development of new drugs. For this reason, studies on aromatic medicinal plants with therapeutic potential have recently increased, mainly due to the proved antimicrobial action of monoterpene compounds as present in essential oils.
Genus Lippia has been intensively studied from the ethnobotanic, chemical and pharmacological point of view. Results from these studies have confirmed anti-inflammatory, larvicide, hypotensive, sedative, analgesic, carminative, antimicrobial, cytotoxic, antioxidant and other pharmacological activities.
Among Lippia species available in Brazil, we highlight: Lippia alba, which essential oil contains about 40% carvone and has bactericidal activity against gram positive bacteriae; Lippia javanica rich in micernone (36-62%), carvone (61-73%), piperitenone (32-48%), ipsenone (42-61%) and linalool (>65%), depending on the growing environment, efficient against the growth of microorganisms Cryptococcus neoformans, Bacillus cereus, Escherichia coli and Staphylococcus aureus, having bacteriostatic effect against Klebsiella pneumoniae and Plasmodium falparium in micromolar concentrations; Lippia multiflora having antioxidant and antimicrobial activity against Pseudomonas aeruginosa and Candida albicans, which action is attributed to carvacrol, one of the major components of the essential oil of that species; Lippia dulcis, which in vivo study performed with swines has shown that the essential oil in 100 μg/ml concentration has anti-histaminergic and anticholinergic activities.
Studies as mentioned above related to antimicrobial activities have emphasized thymol and carvacrol as present in genus Lippia, highlighting Lippia sidoides with high yield of essential oil.
More specifically, such pharmacological studies have confirmed the therapeutic potential of Lippia sidoides, including: confirmed cytotoxic activity over three kinds of cancer cells, i.e. HL60 (leukemia), SW1573 (lung carcinoma) and CEM (lymphoblastic leukemia); anti-inflammatory activity of L. sidoides oil in an experiment with rats; inhibition of the activity of the acetylcholinesterase enzyme indicating potential use in the treatment of Alzheimer; antioxidant activity of thymol and carvacrol as present in its oil; efficacy in the reduction of dental plaque, gingivitis and gum bleeding; antimicrobial activity against S. aureus, C. albicans and E. coli; antifungal activity against Candida albicans, Candida tropicalis and Microsporum canis; antimicrobial activity against gram-positive and gram-negative bacteriae; bacteriostatic activity against various strains of isolated S. aureas from clinical material, resistant to antibiotics; anti-helminths activity, besides having larvicidal activity in the combat against A. aegypti mosquitoes.
To yield a medicine produced from plants synthesizing essential oils, preliminary agronomic research is required, so to supply yielding data as a function of given edaphic and seasonality conditions. The content of essential oil in a plant may vary as a function of the time of the year, stage of development, geographic and ecological factors, as well as genetic variations. Botanically identical plants may be chemically different from each other and, when it happens, they are called chemotypes or chemical races. Chemical variations are characterized by the majority of given compounds in essential oils, which are called major components.
Studies performed by various researchers have shown that L. sidoides present variations in content and quality of oil depending on the place of origin. This data is summarized on Table 1 below.
TABLE 1Composition of essential oil in different chemotypes of L. sidoidesChemotypes (% content)ComponentabcdefghThymol56.6766.6759.6559.6543.580.866.6748.32Carvacrol16.731.814.36.90p-Cymene7.137.138.67.13Thymol methyl5.061.151.791.151.34etherAroma-2.790.531.81dendrene1.8-Cyneol2.391.391.31.398.62γ-Elemene2.281.81γ-Terpinene1.421.133.833.831.64.060.58α-Terpinene1.121.431.431.130.12β-Myrcene0.861.765.435.436.50.91.760.32α-Tujone0.780.731.481.480.73Octen-3-ole0.510.810.810.37p-Cymene7.139.089.088.61.38E-11.7310.60CaryophylleneLimonene1.011.01Di-0.91hydro-aromadendreneCaryophyllene0.721.88Oxideα-Copaene0.660.26α-Humulene0.560.65α-Pinene0.510.510.17α-Muurolene0.45δ-Cadinene0.350.59Linalool0.280.28β-Ocymene0.270.270.50Umbellulone0.460.22Methyl1.79thymyletherβ-9.711.73Caryophylleneα-phelandrende22.4Trans-5.113.77caryophylleneTrans-miroxide1.324-Terpineol1.34α-Terpineol2.27Eugenol0.49γ-Muurolene0.26α-Selynene1.72
Besides essential oil, various other compounds have been isolated from L. sidoides, such as 3-O-acetyloleanolic acid, 3.4 menthol di-hydroxybenzoate, lapachonol, techomaquinone, tectol, tectol acetylate, tectoquinone, quercetin, luteolin, glucoluteolin, taxifolin, isolariciresinol, prenylated naphthoquinone, lipsidoquinone, isocatalpanol and techomaquinone.
There is no information in the literature on similar studies and experiments performed with the species Lippia salvifolia. 